A reactive neural network framework for water-loaded acidic zeolites.

Under operating conditions, the dynamics of water and ions confined within protonic aluminosilicate zeolite micropores are responsible for many of their properties, including hydrothermal stability, acidity and catalytic activity. However, due to high computational cost, operando studies of acidic zeolites are currently rare and limited to specific cases and simplified models. In this work, we have developed a reactive neural network potential (NNP) attempting to cover the entire class of acidic zeolites, including the full range of experimentally relevant water concentrations and Si/Al ratios.

Migration of zeolite-encapsulated subnanometre platinum clusters reactive neural network potentials.

The migration of atoms and small clusters is an important process in sub-nanometre scale heterogeneous catalysis, affecting activity, accessibility and deactivation through sintering. Control of migration can be partially achieved encapsulation of sub-nanometre metal particles into porous media such as zeolites. However, a general understanding of the migration mechanisms and their sensitivity to particle size and framework environment is lacking.

Correction: The need for modelling of Al NMR in zeolites: the effect of temperature, topology and water.

[This corrects the article DOI: 10.1039/D3SC02492J.].

The need for modelling of Al NMR in zeolites: the effect of temperature, topology and water.

Solid state (ss-) Al NMR is one of the most valuable tools for the experimental characterization of zeolites, owing to its high sensitivity and the detailed structural information which can be extracted from the spectra. Unfortunately, the interpretation of ss-NMR is complex and the determination of aluminum distributions remains generally unfeasible. As a result, computational modelling of Al ss-NMR spectra has grown increasingly popular as a means to support experimental characterization.

Dynamical Equilibrium between Brønsted and Lewis Sites in Zeolites: Framework-Associated Octahedral Aluminum.

While the structures of Brønsted acid sites (BAS) in zeolites are well understood, those of Lewis acid sites (LAS) remain an active area of investigation. Under hydrated conditions, the reversible formation of framework-associated octahedral aluminum has been observed in zeolites in the acidic form. However, the structure and formation mechanisms are currently unknown.

Salivary clearance of caffeine in children.

Background: Measurement of salivary caffeine (1,3,7-trimethylpurine-2,6-dione or 1,3,7-trimethylxanthine) clearance can, in principle, be used to assess hepatic function, diagnose chronic hepatic disease and conduct investigations of substrates of hepatic cytochrome P450 (CYP) isozymes in children, without recourse to venepuncture. However, little is known about childhood sexual dimorphism of hepatic CYP isoforms. Furthermore, the association, if any, between salivary caffeine clearance and age in children has not hitherto been established.

A themed collection in memory of Petr Nachtigall.

Professor RNDr. Petr Nachtigall, PhD passed away on 28 December 2022. He was an internationally recognized expert in computational materials science; working at Charles University in the Department of Physical and Macromolecular Chemistry.

Encapsulating Metal Nanoparticles into a Layered Zeolite Precursor with Surface Silanol Nests Enhances Sintering Resistance.

Supported metal nanoparticles are used as heterogeneous catalysts but often deactivated due to sintering at high temperatures. Confining metal species into a porous matrix reduces sintering, yet supports rarely provide additional stabilization. Here, we used the silanol-rich layered zeolite IPC-1P to stabilize ultra-small Rh nanoparticles.

The economics of medical procedure innovation.

This paper explores the economic incentives for medical procedure innovation. Using a proprietary dataset on billing code applications for emerging medical procedures, we highlight two mechanisms that could hinder innovation. First, the administrative hurdle of securing permanent, reimbursable billing codes substantially delays innovation diffusion.

Nanoparticles Supported on Sub-Nanometer Oxide Films: Scaling Model Systems to Bulk Materials.

Ultrathin layers of oxides deposited on atomically flat metal surfaces have been shown to significantly influence the electronic structure of the underlying metal, which in turn alters the catalytic performance. Upscaling of the specifically designed architectures as required for technical utilization of the effect has yet not been achieved. Here, we apply liquid crystalline phases of fluorohectorite nanosheets to fabricate such architectures in bulk.

Zeolite (In)Stability under Aqueous or Steaming Conditions.

Zeolites are among the most environmentally friendly materials produced industrially at the Megaton scale. They find numerous commercial applications, particularly in catalysis, adsorption, and separation. Under ambient conditions aluminosilicate zeolites are stable when exposed to water or water vapor.

Is there a sex difference in adult salivary clearance of caffeine (1,3,7-trimethylpurine-2,6-dione)?

Background: The salivary caffeine clearance is a non-invasive, safe, saliva-based method for assessing hepatic function and diagnosing chronic liver disease. The elimination of caffeine from the body follows first-order kinetics and principally involves catabolism by hepatic CYP1A2, with a half-life usually between three and 7 h. It is known that this process is affected by age and smoking tobacco.

Fast room temperature lability of aluminosilicate zeolites.

Aluminosilicate zeolites are traditionally used in high-temperature applications at low water vapour pressures where the zeolite framework is generally considered to be stable and static. Increasingly, zeolites are being considered for applications under milder aqueous conditions. However, it has not yet been established how neutral liquid water at mild conditions affects the stability of the zeolite framework.

Altering CO binding on gold cluster cations by Pd-doping.

The introduction of dopant atoms into metal nanoparticles is an effective way to control the interaction with adsorbate molecules and is important in many catalytic processes. In this work, experimental and theoretical evidence of the influence of Pd doping on the bonding between small cationic AuN+ clusters and CO is presented. The CO adsorption is studied by combining low-pressure collision cell reactivity and infrared multiple photon dissociation spectroscopy experiments with density functional theory calculations.

Pre-medication before dental procedures: A randomized controlled study comparing intranasal dexmedetomidine with oral midazolam.

Background: This study aimed to determine if intranasal dexmedetomidine is a superior pre-medication to oral midazolam in older, difficult children.

Methods: This was conducted as a prospective, single-blind randomized control trial in a tertiary care center. Seventy-five children, age >5 years and weight >20 kg, who needed general anesthesia for dental procedures were randomly assigned to be pre-medicated with either oral midazolam at a dose of 0.

The effect of water on the validity of Löwenstein's rule.

The common understanding of zeolite acidity is based on Löwenstein's rule, which states that Al-O-Al aluminium pairs are forbidden in zeolites. This rule is generally accepted to be inviolate in zeolites. However, recent computational research using a 0 K DFT model has suggested that the rule is violated for the acid form of several zeolites under anhydrous conditions [Fletcher , , , (2017), 7483].

Towards operando computational modeling in heterogeneous catalysis.

An increased synergy between experimental and theoretical investigations in heterogeneous catalysis has become apparent during the last decade. Experimental work has extended from ultra-high vacuum and low temperature towards operando conditions. These developments have motivated the computational community to move from standard descriptive computational models, based on inspection of the potential energy surface at 0 K and low reactant concentrations (0 K/UHV model), to more realistic conditions.

2D Oxide Nanomaterials to Address the Energy Transition and Catalysis.

2D oxide nanomaterials constitute a broad range of materials, with a wide array of current and potential applications, particularly in the fields of energy storage and catalysis for sustainable energy production. Despite the many similarities in structure, composition, and synthetic methods and uses, the current literature on layered oxides is diverse and disconnected. A number of reviews can be found in the literature, but they are mostly focused on one of the particular subclasses of 2D oxides.

Association between Bispectral Index System and airway obstruction: an observational prospective cohort analysis during third molar extractions.

Background: Sedation regimes during oral procedures frequently associated with airway obstruction. The aim of this study was to define the association of Bispectral Index (BIS) to the depth of sedation and airway obstruction events.

Methods: Forty-seven patients between 14-21 years old, who were candidates for 3rd molar teeth extraction, were enrolled in this study.

The association between misperceptions around weight status and quality of life in adults in Australia.

Background: Limited evidence supports a possible association between a person's perception of their weight status and their quality of life (QoL). This study evaluates whether misperception around weight status is associated with QoL and the impact of gender on this association.

Methods: A cross-sectional survey of Australian adults (n = 1,905 analysed) collected self-reported height and weight (used to estimate BMI), gender and QoL (described using the AQoL-8D).

Extracorporeal Life Support: Four Decades and Counting.

Extracorporeal membrane oxygenation (ECMO) or extracorporeal life support (ECLS) is a form of heart lung bypass that is used to support neonates, pediatrics, and adult patients with cardiorespiratory failure for days or weeks till organ recovery or transplantation. Venoarterial (VA) and venovenous (VV) ECLS are the most common modes of support. ECLS circuit components and monitoring have been evolving over the last 40 years.

Does dexmedetomidine cause less airway collapse than propofol when used for deep sedation?

Study Objective: The risk of airway collapse in patients undergoing deep sedation is a major concern. In this study, we compared the airway patency of deep sedation provided by propofol with the airway patency of deep sedation provided by dexmedetomidine in magnetic resonance imaging (MRI) procedures. This comparison was done using MRI static and dynamic images and comparing these images to baseline after sevoflurane induction.

Noise pollution levels in the pediatric intensive care unit.

Unlabelled: Patients and staff may experience adverse effects from exposure to noise.

Object: This study assessed noise levels in the pediatric intensive care unit and evaluated family and staff opinion of noise.

Design: Noise levels were recorded using a NoisePro DLX.